The present invention relates to a gas, water-vapor and smoke-permeable tubular food casing, in particular a sausage casing, based on a cellulose, preferably a fiber-reinforced cellulose, which is a suitable substrate for a mold overlay, i.e. a culture of mold fungi conducive to the ripening process of sausages. The casing is provided with a synthetic polymeric coating to improve its resistance to degradation of the cellulose by cellulases or other cellulolytic enzymes. The invention also relates to a process for manufacturing this casing and to the use thereof in the production of dry sausages, long-keeping sausages and uncooked sausages.
As is known, tubular food casings comprising fiber-reinforced cellulose are used both for packaging processed meat products, for example, sausage emulsions and poultry slices, and dairy products, for example, cheese in the form of rolls. These food casings, which are also called fibrous casings, usually comprise a web of fiber material, for example a paper web, shaped into a tubing and provided with a cellulosic coating which is particularly produced by applying viscose to the fiber material and then precipitating and regenerating the viscose into cellulose hydrate.
The casings used for packaging various types of sausage products must have different properties. In the case of sausages which are known as dry sausages, long-keeping sausages or uncooked sausages, for example, salami and cervelat sausage, the preservation treatment comprises drying and, if appropriate, smoking of the sausages and, therefore, casings are required, which are permeable to gases, water-vapor and smoke.
High-quality varieties of these dry, long-keeping and uncooked sausages are known which are produced according to the natural ripening process and are covered with a mold overlay on the outside of the cellulosic casing. In this process, the sausages are preserved by air-drying for a prolonged period of time, the usual storage times being two or three months or even longer. For producing sausages by the natural ripening process, it is therefore necessary to have a sausage casing which has a particularly high permeability to water-vapor and shows a good breathing effect. However, the long storage times required in the natural ripening process present certain problems. For example, the mold overlay produces cellulases and other cellulolytic enzymes, which disintegrate the cellulosic casing with increasing storage time. As a consequence, the casing becomes brittle and can no longer be peeled from the sausage meat without breaking, particularly at the end of the storage time.
To solve this problem, U.S. Pat. No. 3,935,320 describes a cellulosic casing provided with a closely adhering coating of a cured cationic resin, for example, a reaction product of epichlorohydrin and a polyamide, which is necessarily present on both sides of the casing. However, even these casings, which are resin-coated on both sides, tend to become embrittled. Particularly, there is a risk that cracks will occur in the resin coatings, when these casings are gathered into sticks, i.e. into shirred tubings, which are used on automatic filling machines for stuffing with sausage meat, for example. Through these cracks, the cellulolytic enzymes of the mold fungi enter into contact with the cellulose, which is thus gradually disintegrated.